This invention relates to flash chambers and more particularly the venting of flash chambers. The flash chamber is the portion of a catheter unit which is held by the medical technician during the insertion (by puncture of the needle carrying the catheter coaxially thereabout) into the lumen of a blood vessel. Once puncture has been made by penetration with the tip of the hollow needle, blood spurts up through the needle and appears to flash into a chamber affixed at the end near the medic (not the patient) of the hollow needle. A tourniquet is used to facilitate the location of the vein and increase local blood pressure thereby causing the spurt. The medical technician knows of successful puncture or penetration into the vein because of the flash into the chamber.
Flash chambers are usually vented by means of an opening at the end remote from where the hollow needle is connected. This opening is covered by a filter in the form of a porous membrane usually of spun bonded polyolefinic material which is lint free and is affixed or held across the opening at the end of the flash chamber that the medic holds. Some flash chambers use a circuitous path to control flow of flashed blood from the needle end of the flash chamber to the end most proximate the medic but still have a filter element. The flash chamber concept is to allow the medic to see when the puncture is successful and yet prevent the spillage of blood during time required for the insertion procedure. Various approaches to making the path in the flash chamber circuitous have been tried, which rely on a change of direction of flow normal to the axis of the needle at least once or several times during the process of venting. The ultimate disposition of the flash blood is at the end of the flash chamber closest to the medical technician.
With the current concern about blood transmitted diseases such as tuberculosis, hepatitis, AIDS, and the like, the fear is that disease will be transmitted if the medical technician contacts the patient's blood. Similarly, the medical technicians are exposed to various other patients and equipment with a variety of infection, contagious diseases, bacteria and/or virus about the hospital whereby flashed blood might pick up same and reach the patient. The problem is to prevent the blood from leaking from the flash chamber near the surfaces where medics normally handle the catheter. These problems have caused concern about the way in which the flashed blood is vented.